Warning:
1, It will be faster and better with Python (3 or 2) enabled Vim. But some old version Vim enabled both Python 2 & 3 may have some issues.
2, If you use Vim in terminal, to avoid the Esc delay, please set 'ttimeoutlen' to 100 or some other value. And check screen's 'maptimeout' or tmux's 'escape-time' option if you use it too.